This invention relates lubricants for food packaging, lubricated packaging business methods and to lubricated food containers and lubricated conveyor apparatus that can move the container or container plus food composition during production. Such conveyors typically move the containers to stations that incorporate the food composition into the container and then further direct the container or food and container to stations that can clean the container, apply labels, seal or package the container for further shipment. The invention relates to lubricating conveyors that support and transport work piece. The invention relates to methods of use, for example, to treat or lubricate a container(s) and conveyor surfaces or system for containers. Containers can be made of glass, metal or plastic. The container is, for example, a food or beverage container. More particularly, the invention relates to a conveyor system for transporting both empty and filled polyester beverage containers of various sizes.
In commercial container filling or packaging operations for foods, beverages and other materials, the containers typically are moved by a conveying system at very high rates of speed. In current bottling operations, copious amounts of aqueous dilute lubricant solutions (often based on ethoxylated amines or fatty acid amines) are typically applied to the conveyor. These lubricant solutions permit high-speed operation (up to 1000 containers per minute or more) of the conveyor and limit marring of the containers or labels, but also have some disadvantages. For example, aqueous conveyor lubricants based on fatty amines typically contain ingredients that can react with spilled carbonated beverages or other food or liquid components to form solid deposits. Formation of such deposits on a conveyor can change the lubricity of the conveyor and require shutdown to permit cleanup. Further, aqueous lubricants are typically used in high volumes resulting in high cost and wastage of lubricant compositions from the conveyor surfaces. Such means to apply the liquid lubricant can create a splash, stream, mist or other directed liquid mass that can contact the food in a container or remain on the container and result in a concentration of lubricant in the food. Consumption of the food or contact with the container can result in the ingestion of the lubricant residue form the food or container.
These commercial aqueous conveyor lubricants, conventionally based on fatty acids, anionic surfactants, ethoxylated amines or fatty amines, are not currently qualified for contact or indirect contact with food. Any contact between food and lubricant can render the food unfit for human consumption under current FDA regulations including for example 21 CFR xc2xa7xc2xa7 1.172, 1.178 and 1.182. These regulations also define xe2x80x9cfood gradexe2x80x9d additive materials. Further, such lubricants typically contain ingredients that can promote microbes or can react with spilled carbonated beverages or other food or liquid components to form unwanted solid deposits.
When first used with beverage containers, such conveyor systems were lubricated using dilute aqueous lubricant materials, typically, substantially soluble sodium salt of the fatty acid or sodium salt of linear alkane sulfonate which acted to both lubricate and at least to some degree, clean the conveyor surfaces. Representative examples of such lubricants are found in Stanton et al., U.S. Pat. No. 4,274,973 and Stanton, U.S. Pat. No. 4,604,220. Many current conveyor lubricant systems are classified H-2 according to regulations in 21 CFR xc2xa7xc2xa7 1.172, 1.178 and 1.182. Such systems are not approved for incidental, indirect or direct contact with beverage compositions. Any contact between H-2 lubricant materials and foods that incorporates any important amount of lubricant into beverage renders the beverage unsuitable for human consumption. Significant problems have arisen when H-2 lubricants have come into contact with food materials. When the food materials, often beverages or other comestibles have been contaminated with such H-2 lubricants, recalls of these materials have occurred resulting in substantial loss to the manufacturer. Because of the safety concerns and the potential of financial lawsuit to manufacturers, the use of H-2 lubricants can often pose substantial operating costs and administrative costs including regulatory review personnel insurance and other costs not directly related to the costs of lubricating conveyor lines and the costs of maintaining food purity. Accordingly, a substantial need exists in the art to obtain lubricants that can be used in a way on lubricating lines and with respect to containers and containers containing food such that the food can come into incidental, indirect or direct contact with lubricating compositions without rendering the food unfit for human consumption.
More recently a series of substantially soluble aqueous lubricants were introduced including Rossio et al., U.S. Pat. Nos. 4,929,375 and 5,073,280; and Wieder et al., U.S. Pat. No. 5,009,801. These patents assert that certain substituted aromatic compounds, certain couplers and saponifying agents and certain amine compounds can inhibit stress cracking in appropriately formulated materials. Other patents, including Person Hei et al., U.S. Pat. Nos. 5,863,874 and 5,723,418; Besse et al., U.S. Pat. No. 5,863,871; Gutzmann et al., U.S. Pat. Nos. 5,559,087 and 5,352,376; Liu et al., U.S. Pat. No. 5,244,589; Schmitt et al., U.S. Pat. No. 5,182,035; Gutzmann et al., U.S. Pat. No. 5,174,914; teach various conveyor lubricants and methods that provide adequate lubrication, cleaning and inhibit stress cracking. Lubricating solutions are often used on conveying systems during the filling of containers with, for example, beverages.
Conventional lub concentrate and diluted lubricants are commonly applied to moving conveyor belts using application equipment typically including nozzles that deliver about 1 to about 5 gallons of lubricant per hour of operation. Often, two or more of the nozzles are placed along the path of the conveyor to maintain sufficient lubricant on the conveyor for effective operations. Such a spray volume and viscosity results in the add-on of substantial volumes of lubricant. A substantial proportion of the lubricant drains from the conveyor surface and ultimately accumulates on surfaces underneath the conveyor, most commonly on the floor of the bottling facility. Such operations result in substantial product wastage, concerns with respect to the biocompatibility of effluents in sanitary drains, foam accumulation on containers, labels, unsafe slippery floors, substantial microbial growth and an overall undesirable aspect.
There are a number of different requirements for such lubricants. For example, the lubricant should provide an acceptable level of lubricity for the system and not adversely affect the conveyor or container. In the beverage industry, the lubricant must be compatible with the beverage so that it does not form solid deposits when it accidentally contacts spilled beverages on the conveyor system. This is important since the formation of deposits on the conveyor system may change the lubricity of the system and could require shutdown of the equipment to facilitate cleaning. The lubricant must be such that it can be cleaned easily. The container and/or the conveyor system may need to be cleaned. Since water is often in the cleaning solution, ideally the lubricant has some water soluble properties.
Currently, containers, including polyethylene terephthalate (PET) bottles, and conveying systems for containers are often contacted with a volume of a dilute aqueous lubricant to provide lubricity to the container so that it can more easily travel down the conveyor system. Many currently used lubricants are diluted at a ratio of about 1:100 with water are disadvantageous because they are incompatible with many beverage containers, such as PET and other polyalkylene terephthalate containers, and may promote stress cracking of the PET bottles.
Furthermore, aqueous based lubricants are in general often disadvantageous because of the large amounts of water used, the need to use a wet work environment, the increased microbial growth associated with such water-based systems, and their high coefficient of friction. Moreover, most aqueous-based lubricants are incompatible with beverages.
Flooding a conveyor surface with a substantial proportion of aqueous lubricant typically occurs on food container filling or beverage bottling lines. Sufficient lubricant is used such that the lubricant is not retained entirely by the surface of the conveyor but tends to flow from the surface of the container, drip onto a conveyor support members and the surrounding environmental area around the conveyors. Further, sufficient amounts of lubricant are applied to the conveyor and other mechanisms of the plant under such conditions that a substantial foam layer of lubricant can form on the surface of the conveyor. As much as one inch (about 2.5 cm or more) thick of lubricant foam can contact a substantial portion of the base of a food container such as polyethylene terephthalate beverage bottle. We have found that current methods of lubricating such containers are wasteful of the lubricant material since a substantial proportion of the materials is lost as it leaves the container surface. Further, substantial proportions of the lubricant remain on the container and are carried from the conveyor as the food packaging or beverage-bottling operations are continued. A substantial need exists for approved methods that waste little or no lubricant during packaging or bottling operations. Current lubricating methods for conveyors of beverage containers typically include flooding the conveyors with aqueous lubricants in relatively large add-on amounts. Such technology involves the high volume use of aqueous lubricants, a fairly high waste of the aqueous lubricant because the material tends to drip from the conveyor and contaminate the bottles.
In certain lubrication methods, liquid lubricants are added to a conveyor using a brush or high density felt cloth (see for example U.S. Pat. No. 6,102,161 or WO 00/01979) application means and method. Such brush or cloth application is associated with a reservoir or manifold containing the liquid lubricant that is added to the system. The lubricant flows through the applicator fibers and, where the fiber contacts the moving conveyor, is intended to apply a substantially continuous film of the lubricant to the conveyor surface. Such applicator usage results in wear and deformation on the applicator mechanism, can cause uneven add on, can be a location for the accumulation of substantial amount of dirt and microbial contamination and can cause other problems associated with worn applicator fiber.
A substantial need exists for improved lubricating methods commonly used in the food or beverage industry. Preferably, the dispensing system of a useful improved lubricant employs relatively low volume nozzle application that is applied in a fashion that sufficient lubricant is applied to the conveyor without wastage. Such operations result in low lubricant dosage on the containers and conveyor, minimal lubricant consumption, reduced wastage of the lubricant and minimal foam accumulation, little overspray, use of viscous materials that reduce dripping, reduced moisture, reduced microbial growth, improved appearance and safety concerns combined with a dispenser that does not come in direct physical contact with the conveyor. Such a system should be useful with a broad variety of lubricant materials that can be spray applied as disclosed below. The lubricant of these methods is preferably made of materials that are H-1 approved and can be contacted with the food or considered to be a food additive and not result in the food being rejected as not fit for human consumption.
We have surprisingly found that a controlled application of a liquid lubricant (qualified as H-1) in the finely divided form of a stream of divided droplets, particulates, mist or fog of the lubricant can be an effective means for applying lubricant uniformly to a moving conveyor. A size for the finely divided lubricant is selected such that the finely divided material after formation in the lubricating apparatus fall under the influence of gravity directly to the conveyor and substantially all of the lubricant particles contact and remain on the surface such that the conveyor surface interface between a work piece and the conveyor surface is well lubricated. The sprayed particulate forms a coating of the lubricant that can be continuous or discontinuous on the conveyor can be applied continuously in a continuous stream of droplets or not continuously in a the form of a discontinuous stream intermittently applied. The lubricant layer, in the form used to lubricate the interface between the conveyor and the work piece can provide substantial lubrication. We have found that the formation of a particle size of a particular dimension, about 500 to 2500 microns, is important for forming an effective lubricating method. Particles of such a size are not lost in the form of a mist or fog of the lubricant. Such particles readily fall onto, form a layer and remain on the conveyor under the influence of gravity. However, the particles are not of such a large size that the particles cause an overuse or wastage of lubricant. Importantly, the lubricant falls on the conveyor in amounts and in a position that little or no lubricant drips from the conveyor, preferably the lubricant is maintained in a zone on the conveyor leaving a boarder substantially free of lubricant. In the event that an amount of the spray or droplets of the lubricant comes in direct contact with a food or beverage material intended for human use, a lubricant is used that is classified xe2x80x9cH1xe2x80x9d such that the food containing the lubricant does not become unfit for human consumption.
We have surprisingly found that a relatively low rate of add-on of the droplets of the preferred particle size provides excellent lubrication, the spray droplets of the invention can be produced using a variety of techniques in which the aqueous lubricant is finely divided into droplets of the appropriate size and directed to the conveyor surface. Included in such methods are use of an air stream to shear the liquid into drops of the appropriate size, a spinning disk method that, when contacted with the liquid lubricant, results in a radial spray of the lubricant or other methods of producing the finely divided lubricant droplet spray.
We have further surprisingly found that forming a controlled flow of air and directing a flow of liquid lubricant into the airflow can form droplets of the preferred size and obtain a degree of lubrication adapted to the beverage conveyors. In order to form the correct particle size of the dispersed lubricant, a surprisingly low pressure and relatively low volume per minute flow of air is established and that flow of air is directed into a flow of the lubricant. The lubricant also directed at a relatively slow rate. Preferably, the lubricant is directed into the air stream at an angle substantially normal to the flow of air. The established flow of air, at a pressure of about 0.1 to 20 or about 0.1 to 10 psi and at a low CFM flow rate of about 10 to 25 milliliters of air per second is established through an appropriately sized nozzle. The liquid lubricant is directed into the air stream at a flow rate of about 0.1 to 10 milliliters-secxe2x88x921 (about 1500 to 4000 mL-hrxe2x88x921). We have found that the liquid lubricant is sheared by the air flow and produces a particle size in the order of about 100 to 5000 microns, preferably 500 to 2500 microns. The air stream is directed at an angle appropriate to directing the resulting stream of finely divided particulates onto the conveyor system. The add-on angle can be parallel to the conveyor. The air and lubricant flow are controlled such that greater than about 90% of the lubricant is directed onto the conveyor surface at an add on rate of about 5xc3x9710xe2x88x924 to 0.02 grams-inxe2x88x921 establishing a coefficient of friction between the conveyor and the work piece of less than about 0.14 preferably less than 0.1.
A preferred lubricated conveyor system for transporting a work piece from a first work station to a second work station comprises a moving conveyor belt associated with a mechanism for producing a divided distribution of droplets as described above of liquid lubricant. The lubricating means comprises an air manifold, an air injection means, and a lubricant injection means. The lubricant is directed into the air flow at a rate that produces a droplet of about 100 to 5000 microns and the air flow is controlled such that greater than 90% of the lubricant falls on the container or the conveyor belt. Preferably, the lubricant falls substantially on the conveyor belt under the influence of gravity. The conveyor can be operated to move at a rate that conveys about 200 to 2000 bottles per minute, the interface between the bottles.
Conventional spray equipment typically used in paint application, sanitizing and other applications, typically involves high pressure air stream, high liquid flow rates, designed and engineered to insure that the surface contacted by the spray obtains a high loading in a very short amount of time of the material delivered by the spray. Paint sprayers, for example, deliver high volumes of paint at pressures of about 2000 to 6000 psi in order to provide a paint coating that can be formed quickly and uniformly across a large area of surface. Spray equipment, either in an airless or an air driven spray system are typically engineered so that the spray, in a particular spray pattern, delivers a large amount of material in an efficient transfer to a surface. The development of spray equipment and processes has largely been directed to using high pressure and large volume amounts of spray.
We have also found that the lubricating systems are well adapted to food grade or H-1 lubricants. Any spray that is conveyed onto or into the food in a container must not render the food unfit for human consumption. The use of an H-1 grade lubricant in such a conveyor system can alleviate many concerns with respect to contacting the food material with the lubricant material. Should some amount of the lubricant come into direct, incidental or indirect contact with the food, the presence of the H-1 lubricant in the food does not render the food unsuitable for human consumption. xe2x80x9cFoodxe2x80x9d as used in this application means any substance ingested by humans including liquid, solid, semi-solid, composite comestible materials in the form of water, carbonated beverage, a food, juice, sports beverage, snack, edible container or carrier. Such a process an result in substantial savings in the operation of the food manufacturing and packaging operation and can also result in substantial savings of money in general administrative and operating expenses by reducing costs of recall of contaminated materials (in contact with H-2 lubricants) and in reduced administrative costs such as reduced insurance costs. U.S.D.A. H-1 lubricants are regulated in 21 C.F.R. xc2xa7 178 (at 178.3570), 21 C.F.R. xc2xa7 1.72 and 21 C.F.R. xc2xa7 1.82. The materials are formulated to contain ingredients that both lubricate and pass the stringent guidelines of the Federal regulations. For the purposes of this application the terms xe2x80x9cDirect, Incidental or Indirectxe2x80x9d contact between lubricant and food means that the food acquires an amount of lubricant. This amount if in the form of an H-2 composition would render the food unfit for human consumption. For the purpose of this specification and claims, the term xe2x80x9ccoatingxe2x80x9d is intended to mean a continuous or discontinuous thin liquid layer of the lubricant dispersions of the invention on a moving conveyor surface. Applying the liquid to the surface such that the surface of the conveyor is substantially completed covered with the lubricant can form such a coating. Alternatively, the term xe2x80x9ccoatingxe2x80x9d can also connote the continuous or the intermittent timed application of the lubricant such that the lubricant can be applied intermittently to a surface of a moving conveyor. The intermittent application of the lubricant can form a continuous layer and still provide an adequate lubricating layer on the surface. The lubricant coatings of the invention can develop areas of the conveyor that do not have any substantial quantity of liquid lubricant as the lubricant interacts with the conveyor surface, the containers and the changing conditions as the conveyor moves through the structure. For the lubricant to work successfully, there must be an amount of lubricant at the container conveyor interface to obtain reduced coefficient of friction. In other words, a successful lubricant coating is present when the lubricant is present at the interface to successfully reduce friction during conveying of a container from place to place on a conveyor.